On Thursday morning, San Diego Gas & Electric (SDG&E), finally sunk a shovel into the ground for the transmission project every enviro loves to hate: The 100-mile, $1.9 billion, 500-kilovolt Sunrise Powerlink, slated to skim across desert-and-forest wilderness as it carries power to the hamlet sprawl along California’s southernmost coast. Arnold Schwarzenegger, ever more flamboyantly emotional in his final weeks as California’s governor, gave a rousing speech at the event; utility executives smiled broadly and shook his hand.

But groundbreaking day for the Powerlink was not perhaps as cheery as its proponents had hoped. First came the 150 protesters from environmental groups who mobbed the Governor’s motorcade, shoving placards neatly imprinted with anti-development quotes from Aldo Leopold in his face. Then followed more prosaic bad news: The developer behind one of the key projects packaged with the Powerlink, Stirling Energy System’s Imperial Solar plant, saw its CEO, Steve Cowman, walk out the door.

The rumored and apparent reason: In order to qualify for federal stimulus loans expiring at the end of the year, the companies need to raise hundreds of millions dollars. And, thanks to a combination of controversy and the fickle trends of energy technology, that doesn’t seem likely to happen.

Energy transitions are expensive, and all the more so when the energy source in question is neither demonstrated nor particularly popular. Indian tribes and environmental groups have hammered Stirling’s sister company, Tessera Solar, with lawsuits, and a protest movement is stirring up among residents of Colorado’s San Luis Valley, where the company has staked out ground for another solar development.

The developers’ worst problem, however, may be the technology itself, which has simply never been deployed on a scale anywhere close to what Tessera and Stirling have proposed.

The Imperial Valley plant would have used “Dish Stirling” technology, which uses massive concave mirrors to catch the sun’s heat, focus it on a fluid and run a Stirling engine. Dish technology is more efficient than the parabolic trough or power tower versions of concentrating solar power (CSP), and it uses no water. But unlike more conventional CSP, the dish system has no storage capacity, and its moving parts may not be resistant to the environmental challenges of the desert environment. And though few analyses have nailed down its costs, it's probably expensive: Estimates range from $5 to 6.50 per watt."

At the same time, plain old road-tested solar photovoltaic technology, the kind you can slap on the roof or use to cover Southern California’s sunny warehouses, keeps marching ahead, its price dropping down around $3 a watt this year, and headed for $2 a watt in 2020. Several solar developers have already moved from CSP to photovoltaics for their plants, which does little to placate conservationists – solar has a huge footprint any way you cut it -- but at least doesn’t crush the developers with debt.

By contrast, the Irish conglomerate NTR, which owns both Stirling and Tessera, posted a $278 million loss for last quarter. On the very day of the groundbreaking, the Irish Times reported NTR's announcement that it's postponing its Imperial Valley and Mojave Desert solar projects. And last month, Tessera laid off half its employees, even though the 8,000 acre Calico Solar plant in the Mojave had finally been approved on December 2 by the California Energy Commission.

All of that was somewhat satisfying news – in a we-told-you-so sort of way -- to the conservation groups who vigorously battled the Sunrise Powerlink over the years, filing reams of legal documents in defense of everything from bighorn sheep to plain old peace and quiet. But Imperial Solar's problems looked bad for SDG&E, which had sold the transmission line on the grounds that utilities in California desperately need renewable energy to meet the state’s 33 percent by 2020 renewable energy standards. The utility has argued – but not promised – that the line will carry mostly carbon-free power, including geothermal power from land near the Salton Sea, wind from the breezy Mexican border and concentrating solar power from a desert where you can fry an egg on a rock in April.

But without the Imperial Valley project, which at 709 megawatts would have pumped out half the power of a modern-day coal-fired plant, there’s not that much green power for the Powerlink to plug into. The utility has contracts for only 60 megawatts of the region’s coveted 2,000 megawatts of geothermal power; wind from plants on tribal lands could put as much as 160 megawatts on the grid. That’s enough to power more than 100,000 homes, but not quite enough to justify the costly endeavor to ratepayers; due to its location, the Powerlink project has run up costs few transmissions lines have ever face: Among the mitigation efforts the utility agreed to is a fleet of high-tech helicopters that will carefully place towers in places too pristine for roads.

So will the utility cancel the corridor? Not a chance, says Bill Powers, a mechanical engineer who’s long been one of the project’s most vocal detractors. “There’s plenty of power for the Powerlink to connect to if the dish solar project in Imperial County is a mirage,” including the 1,250 megawatt Mesquite combined cycle plant Sempra Energy, SDG&E’s parent company, owns in western Arizona, and another 600 megawatt plant in Mexicali, Mexico. “It’s just not green power.”

Judith Lewis Mernit is a High Country News contributing editor. She writes from California.